1. Field of the Invention
The present invention is a technology related to a switch device system for passing/interrupting an electrical signal or turning power on/off.
2. Description of the Related Art
As conventional technologies for energization/shutdown of AC power, for example, there are the following technologies. In a first conventional technology, energization/shutdown of AC power is performed in such a manner that AC contacts are closed/opened by on/off operation of a power switch. A second conventional technology is related to, for example, a projector device without a main switch, and the device is started up and set up for off after use by means of a push-button switch; after the setup for off, an AC plug is pulled out of a socket.
In general, these first and second conventional technologies are mainstream; however, the first conventional technology has a problem, for example, that if AC power supply is interrupted by sudden on-to-off operation of the power switch at the timing at which device off setup is not ready, such as when an HDD is in operation or during cooling of a DC power source or a heating unit, the device may be broken.
Furthermore, the second conventional technology can certainly set up for off of a device just like the first conventional technology; however, there are problems that as long as the AC plug is being inserted into the socket, AC power for detection of the push-button switch and setup for on is consumed all the time, so it is not possible to meet energy saving, and the device is not user-friendly.
To solve these problems, in a third conventional technology, the operation of a toilet fan switch is employed in energization/shutdown of AC power, and an on/off state of switch operation is configured to be detected by a different switch or a detecting means; upon detection of off, a device off setup process is promptly performed to prepare for subsequent showdown of AC power triggered by a clockwork timer of the fan switch.
This third conventional technology is superior in terms of certain device off setup with respect to showdown of AC power and no wasted power consumption; however, there are problems that the mechanical structure is somewhat complex and there is an increase in production costs. Furthermore, even if the device off setup is completed in a short time, it takes a predetermined time to shut down the AC power, so it may cause some wasted power consumption.
To solve such a problem, in a fourth conventional technology, relay contacts are provided in parallel with AC contacts of a power switch, and a switch and a relay are combined as a switch unit, and an electronic timer means is provided. This fourth conventional technology can solve the problems of the third conventional technology, but has problems that the switch unit increases several times in size as compared with the existing power switch, and twice as many AC contact circuits are required, and there is always wasted power consumption for excitation current constantly passed through the relay while the power switch is on and for operating the timer. Furthermore, even if the device off setup is completed in a short time, it takes a predetermined time to shut down the AC power, so the problem of some wasted power consumption still remains.
Therefore, in a fifth conventional technology, the switch and the relay in the fourth conventional technology are separated, and a different switch or detecting means capable of detecting an on/off state of switch operation is provided to the switch unit, and no timer is mounted. The fifth conventional technology employs a method to perform off control of excitation power of the relay upon completion of a device off setup process after detection of off.
This fifth conventional technology is superior in terms of the certainty of execution of the device off setup process upon detection of the off state of switch operation and execution of shutdown of AC power immediately after completion of the device off setup process. However, in this fifth conventional technology, the problems that twice as many AC contact circuits are required and there is wasted power consumption for excitation current constantly passed through the relay while the power switch is on still remain. Furthermore, there is a problem of an increase in space to provide the different switch or detecting means.
For example, Japanese Patent Application Laid-open No. 2002-008490 and Japanese Patent Application Laid-open No. 2002-159143 disclose the conventional technologies as described above.
Therefore, there is a need for a switch device capable of: (1) safety shutdown of the apparatus even in the event of sudden turn-off of a power switch; (2) shutdown of AC power by operation of the power switch when the apparatus is not in use; (3) less wasted power while the apparatus is in operation; (4) less wasted power while the apparatus is in off mode; (5) saving of the space required for the switch and necessary parts as much as possible; (6) production at lower cost; and (7) implementing turn-off of switch contacts with certainty even in the event of out of control due to CPU runaway or the like and enabling a user to recognize such an abnormal condition.